PG + extconf failed, exit code 1 in Linux

Building native extensions. This could take a while...
ERROR: Error installing pg:
ERROR: Failed to build gem native extension.

current directory: /usr/local/rvm/gems/ruby-2.3.0/gems/pg-0.18.4/ext
/usr/local/rvm/rubies/ruby-2.3.0/bin/ruby -r ./siteconf20160831-5454-1endyls.rb extconf.rb
checking for pg_config... yes
Using config values from /usr/bin/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.